This disclosure concerns an invention relating generally to ladders and stairways which are collapsed or otherwise converted between an in-use state and a stowed or hidden state.
Foldable stowing stairways, which may be folded upwardly into the ceiling or towards another elevated level or surface, are known from U.S. Pat. Nos. 4,281,743 and 4,541,508. Such foldable stowing stairways are advantageous because they allow a stair to be folded out of the way when space concerns are present, so that the stair no longer occupies floor space on the lower floor or other surface from which a user wishes to ascend. Such stairways essentially amount to articulated ladders wherein the siderails of the ladders are jointed to allow them to be folded up, and then the folded siderails may themselves be folded between opposing joists of a ceiling to fully stow the stairways.
Such stairways are unsatisfactory in several respects. First, the jointed/articulated nature of their siderails tends to make them lack rigidity, and they can be somewhat wobbly when a user climbs them. It is also often difficult for users to elevate their siderails to complete their folding, particularly if the user is short or lacks upper body strength. Additionally, apart from the difficulty and inconvenience of folding an articulated ladder, the articulated ladders also suffer from the disadvantage of more rapid wear (and inherently limited load capacity) owing to the weakness of the folding joints.
The invention, which is defined by the claims set forth at the end of this document, is directed to stowing stairways which at least partially alleviate the aforementioned problems. A basic understanding of some of the preferred features of the invention can be attained from the Detailed Description provided later in this document.